Is GHG Theory/GW in conflict with Kinetic Theory of Gases?

[guidoLaMoto]

Hi, Folks,...new around here. Please excuse my naivete, but--

I have a problem with the physics behind GHG Theory/GW. Most discussions seem to center around absorbtion/transmission spectra of gases, their correlation with temperature, ala' Black Box radiation and such, and the fact that GHG have that extra degree of freedom (vibration) not possesed by smaller molecules...In so doing, the more basic relationship, according to the Kinertic Theory of Gases, is ignored, that temperature represents an average of the kinetic energy (translational mode) of the individual gas molecules.

Absorbing only those quanta at its resonant frequency to enhance vibration, the GHG molecule immediately re-radiates the quantum at the same frequency. That means (a) only another similar GHG molecule can absorb it again, (2) vibration does not equate with tranlation (ie- kinetic energy) therefore should not affect the actual temp of the air, and lastley, if the absorbtion/re-transmission process takes no time, how does that quantum stay in the atm longer than if it were to pass right on out from surface to space? (counter-intuitive, but we are talking QM here)

Are we justified in using phenomena observable only on the quantum level to macro-world physics?

 

[vanhees71]

Maybe it's a stupid question, but what's GHG? I've never seen that acronym. Also GW (which for me means "gravitational wave(s)") doesn't make sense with the context.

 

[BvU]

Hello @guidoLaMoto,

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As you can see, explaining abbreviations when first using them is a good habit. Either that, or providing links for reference. Some abbreviations have totally different meanings in other contexts and/or cultures !

Even after googling those terms, I'not sure I understand the problem you describe. Do you have a reference where this basic relationship is explicitly swept under the rug ?

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[Bystander]

"GHG" equals green-house gases; "GW" equals global warming.

 

[vanhees71]

Ok, but then if the vibrational modes of the air molecules become relevant, we've indeed no more problems, because than it's no more "global warming" but "global cooking" :-), and humans won't be there anymore to bother about anything.

 

[guidoLaMoto]

Even after googling those terms, I'not sure I understand the problem you describe. Do you have a reference where this basic relationship is explicitly swept under the rug ?

There are many fora/blogs devoted to the question of GW/Climate Change. Most of the discussions talk about the Stefan-Boltzmann Law as it relates wavelength/frequency of emitted radiation to temperature, whereas Guy Lussac/Ideal Gas Law relates molecular kinetic energy to T (& P & V). I've never read anyone mention The Ideal Gas Law (except to counter the argument often used by "The Warmists" about [co2] & temp on Venus...Venus has an atm 9x denser than Earth's, so by PV = nRT, T should be 9x higher. No need to bring CO2 into the discussion.

The GHG Effect is supposedly due to the energy absorbed at specific wavelengths by the gas molecules capable of exhibiting a vibrational mode (in addition to translational and rotational modes). That energy is then re-admitted, each quantum in a random direction. Half, would be "reflected" back down, so to speak, while half would be transmitted upward. That half reflected (for lack of a better word) would presumably take longer to exit the atm into space, resulting in slower cooling of the atm at night (as opposed to actual "heating up").

My confusion is this-- if T is related to translational (kinetic) energy, but increased vibrational energy does not effect kinetic energy, then why should those specific quanta absorbed at the resonant freqency, affecting only the vibrational mode, also affect atmospheric temperature?

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[guidoLaMoto]

Still no takers?...Are you guys stumped too, or just disinterested?
How 'bout this?-- Back when Charles & Guy-Lussac were working, they didn't know about sub-atomic pariticles. To them, kinetic energy was translational energy...Now we know about sub-atomics and the movement within the electron cloud is also kinetic energy...That vibrational mode can transmit its energy to any other molecule by conduction, even if the quantum at the resonant frequency can only be transferred by radiation to another identical molecule.

But that still leads to a weakness in the concept of special attributes of the so-called GHGs in regards to atmospheric temps. Any increases in absorbtivity is merely concelled by an equivalent increase in emissivity...or not? (Kirchoff's Law)